Occurrence of biogenic amines and their correlation with bacterial communities in the Ivorian traditional fermented fish adjuevan during the storage

Adjuevan is an Ivorian traditional fermented fish used as a condiment. However, the fermentation process and storage conditions may lead to the production of biogenic amines (BA) which can induce severe human toxicological effects. Thus, this study aimed to reveal the bacterial community diversity and the BA contents during the storage. Samples of adjuevan from the fish species Chloroscombrus chrysurus, Galeoides decadactylus, and Thunnus thynnus were collected from local producers, stored at ambient temperature (28-30 °C) and in a refrigerator (4 °C) over a period of 8 weeks. At 2-week intervals, BA were determined by HPLC and the bacterial communities analyzed using high-throughput sequencing (NGS) of the V3-V4 region of the 16S rRNA gene. Results showed that histamine, cadaverine, putrescine, and tyramine were the major compounds. In adjuevan from T. thynnus, the level of histamine was over the maximum level of 200 mg/kg determined by Codex Alimentarius. For the other amines, no safety concerns are related. In total, 21 bacterial genera with a relative abundance ≥ 1% and belonging to 14 families and 5 phyla were detected. The Bacillaceae family was the most found at ambient temperature while Staphylococcaceae and Enterococcaceae were the most abundant in a refrigerator. The analysis of correlation showed that the increase of Lentibacillus leads to a decrease of the major BA at ambient temperature. On the contrary, the increase of Staphylococcus, Lactobacillus, Psychrobacter, Peptostreptococcus, and Fusobacterium leads to an increase of these biogenic compounds. Thus, Lentibacillus acted as BA-oxidizing bacteria while the others were found as BA-producing bacteria during adjuevan storage.

Variation of Microbiological and Biochemical Profiles of Laowo Dry-Cured Ham, an Indigenous Fermented Food, during Ripening by GC-TOF-MS and UPLC-QTOF-MS

Fermented foods have unique microbiota and metabolomic profiles that can support dietary diversity, digestion, and gut health of consumers. Laowo ham (LWH) is an example of an indigenous fermented food from Southwestern China that has cultural, ecological, economic, and health significance to local communities. We carried out ethnobiological surveys coupled with metagenomic and metabolomic analyses using GC-TOF-MS and UPLC-QTOF-MS to elucidate the microbiota and metabolic profiles of LWH samples at different ripening stages. The results from high-throughput sequencing showed a total of 502 bacterial genera in LWH samples with 12 genera of bacteria and 6 genera of fungi identified as dominant groups. This is the first study to our knowledge to report the bacteria of Lentibacillus and Mesorhizobium along with fungi Eremascus and Xerochrysium on a fermented meat product. Findings further revealed that the metabolite profiles among LWH samples were significantly different. In total, 27 and 30 metabolites from GC-TOF-MS and UPLC-QTOF-MS analysis, respectively, were annotated as highly discriminative metabolites. Among the differential compounds, the relative contents of most amino acids showed the highest in the LWH sample ripened for two years, while some metabolites with potential therapeutic effects such as levetiracetam were the most abundant in the LWH sample ripened for three years. The correlation analysis indicated that the dominant microbes were closely related to differential metabolites, highlighting the importance of their functional characterization. Findings indicate that the consumption of LWH contributes to microbiological and chemical diversity of human diets as well as suggests efficacy of combining GC-MS and LC-MS to study the metabolites in dry-cured meat products.

Lentibacillus cibarius sp. nov., isolated from kimchi, a Korean fermented food

Two bacterial strains designated NKC220-2^T and NKC851-2 were isolated from commercial kimchi from different areas in Korea. The strains were Gram-positive, aerobic, oxidaseand catalase-positive, rod-shaped, spore-forming, non-motile, and halophilic bacteria. Both strains grew without NaCl, unlike type species in the genus Lentibacillus. The optimal pH for growth was 8.0, higher than that of the type species in the genus Lentibacillus, although growth was observed at pH 5.5-9.0. 16S rRNA gene sequence-based phylogenetic analysis indicated that the two strains (99.3-99.9% similarity) are grouped within the genus Lentibacillus and most closely related to Lentibacillus juripiscarius IS40-3^T (97.4-97.6% similarity) isolated from fish sauce in Thailand. OrthoANI value between two novel strains and Lentibacillus lipolyticus SSKP1-9^T (79.5-79.6% similarity) was far lower than the species demarcation threshold. Comparative genomic analysis displayed differences between the two strains as well as among other strains belonging to Lentibacillus. Furthermore, each isolate had strain-specific groups of orthologous genes based on pangenome analysis. Genomic G + C contents of strains NKC-220-2^T and NKC851-2 were 41.9 and 42.2 mol%, respectively. The strains contained meso-diaminopimelic acid in their cell walls, and the major menaquinone was menaquinone-7. Phosphatidylglycerol, diphosphatidylglycerol, and an unidentified glycolipid, aminophospholipid, and phospholipid were the major polar lipid components of both strains. The major cellular fatty acids of the strains were anteiso-C_15:0 and anteiso-C_17:0. Based on phenotypic, genomic, phylogenetic, and chemotaxonomic features, strains NKC220-2^T and NKC851-2 represent novel species of the genus Lentibacillus, for which the name Lentibacillus cibarius sp. nov. is proposed. The type strain is NKC220-2^T (= KACC 21232^T = JCM 33390^T).

Lentibacillus lipolyticus sp. nov., a moderately halophilic bacterium isolated from shrimp paste (Ka-pi)

A Gram-stain-positive, aerobic, spore-forming, moderately halophilic bacterium, SSKP1-9^T, was isolated from traditional salted shrimp paste (Ka-pi) produced in Samut Sakhon Province, Thailand. This strain grew optimally at 37-40 °C, pH 7.0 and in the presence of 8-16 % (w/v) NaCl. The 16S rRNA gene sequence similarity values between strain SSKP1-9^T and Lentibacillus juripiscarius TISTR 1535^T and Lentibacillus halophilus TISTR 1549^T were 98.7 and 97.2 %, respectively. Based on 16S rRNA gene sequence similarity, strain SSKP1-9^T represents a distinct novel species, as shown by phenotypic traits, DNA-DNA hybridization and average nucleotide identity values. In addition, the whole-cell protein profile confirmed the novelty of the taxon. The genomic DNA G+C content was 44.6 mol%. The major isoprenoid quinone was MK-7. The cell-wall peptidoglycan contained meso-diaminopimelic acid. Polar lipid analysis revealed the presence of phosphatidylglycerol, diphosphatidylglycerol, four unidentified lipids, an unidentified phospholipid and an unidentified glycolipid. The major cellular fatty acids were anteiso-C_15 : 0, anteiso-C_17 : 0 and iso-C_16 : 0. The results of phenotypic and chemotaxonomic characteristics and whole-genome analysis support that strain SSKP1-9^T represents a novel species of Lentibacillus, for which the name Lentibacilluslipolyticus sp. nov. is proposed. The type strain is SSKP1-9^T (=JCM 32625^T=TISTR 2597^T).

Marinilabilia rubra sp. nov., isolated from a marine solar saltern

A novel cherry-red-pigmented, Gram-stain-negative, gliding, facultatively anaerobic and rod-shaped bacterium, designated strain WTE16^T, was isolated from a sediment sample taken from a marine solar saltern of Wendeng, China (36° 59' 56.49'' N 122° 1' 38.84'' E). The novel isolate was able to grow at 20-40 °C (optimum 33 °C), at pH 6.0-9.0 (optimum pH 7.0) and with 1.0-12.0 % (w/v) NaCl (optimum 3.0-5.0 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that the most closely related validly published species is Marinilabilia salmonicolor JCM 21150^T (96.0 % similarity). Average nucleotide identity, average amino acid identity, percentage of conserved proteins and digital DNA-DNA hybridization values between strain WTE16^T and Marinilabilia salmonicolor JCM 21150^T were 73.8 %, 73.5 %, 63.4 % and 19.5-24.2 %, respectively. The genomic DNA G+C content of strain WTE16^T was 40.8 mol%. Chemotaxonomic analysis showed that the sole respiratory quinone was menaquinone 7 (MK-7), and the major fatty acids included iso-C15 : 0 and anteiso-C15 : 0. The polar lipid profile of strain WTE16^T included phosphatidylethanolamine, three unidentified phospholipids and three unidentified lipids. On the basis of its phylogenetic, phenotypic, chemotaxonomic, genotypic and genomic characteristics, strain WTE16^T is suggested to represent a novel species of the genus Marinilabilia, for which the name Marinilabilia rubra sp. nov. is proposed. The type strain is WTE16^T (=KCTC 62599^T=MCCC 1H00311^T).